1. Field of the Invention
This invention relates to an ultrasonic bonding equipment for manufacturing a semiconductor device, a semiconductor device and its manufacturing method. More specifically, the invention relates to the ultrasonic bonding equipment for electrically connecting a lead as an external terminal of a semiconductor device with a electrode provided on an upper surface of a semiconductor chip by a bonding strap having a shape of a plate, a ribbon or the like, and made of aluminum or the like, the semiconductor device manufactured thereby and its manufacturing method.
2. Background Art
A semiconductor device is known in which a lead extending as an external terminal of the semiconductor device is electrically connected with an electrode formed on a surface of a semiconductor chip by a bonding strap having a shape of a plate or a ribbon and made of aluminum or the like. In most instance, the bonding strap is connected to the surface of the semiconductor chip and to the lead consisting of a lead frame by an ultrasonic bonding equipment.
The conventional ultrasonic bonding equipment for manufacturing the semiconductor device has a tip portion (i.e. bonding-tool) for propagating ultrasonic vibration, which has a top surface which is faced to a member to be bonded. The top surface which is faced to the member to be bonded is planar and a plurality of top protruding portions having a shape of a quadrangular frustum are provided on the top surface (Japanese Laid-Open patent Application No. H9-108853 and No. 2002-314018). However, an operating rate of the conventional ultrasonic bonding equipment is low and a running cost is high because an exchange frequency of the bonding-tool is high due to a rapid wear-out of the inclined surface of the top protruding portions which propagate an ultrasonic vibration. Especially, the inclined surfaces of the top protruding portions, which are parallel to a vibration direction of the bonding-tool are worn rapidly.
It is described in a Japanese Laid-Open patent Application No. H5-235115 that the ultrasonic bonding equipment for manufacturing the semiconductor device having irregularities on a bonding surface of the bonding-tool makes it possible to obtain a higher reliable connections by ultrasonic vibration with a lower output power.